String sign

String Sign

    This is a medical term used in diagnosing the Hypertrophic Pyloric Stenosis ("HPS").

    Specifically, it is a radiographic finding on an "Upper GI" series (Upper Gastrointestinal Series) in which the infant is given a radio-opaque material, such as barium, to drink and then x-rays are taken of the infant's stomach and intestines.

    If the infant has HPS, the pylorus is narrowed and the barium, as it flows through the pylorus, will take on the appearance of a thin string, hence the name.  Often, there are several of these strings seen (called the "railroad sign").

    The use of the Upper GI series for the diagnosis of HPS has been largely replaced by the use of Ultra Sound, which can visualize the thickened pylorus and give actual measurements of this thickening.